Parental substance abuse is a leading determinant of child maltreatment and, consequently, is often linked with detrimental clinical outcomes for children, exorbitant fiscal costs for the child welfare system, and serious social costs for our nation. Yet, in spite of the gravity of child maltreatment in the context of parental substance abuse, substance abusing parents rarely receive evidence-based treatments for their problems. Rather, such parents are usually referred from the child welfare system to the adult substance abuse system. Unfortunately, the adult substance abuse treatment system rarely provides the type of outreach needed to engage the parents in treatment or the intensity and breadth of services needed to place these parents and families on more productive life trajectories. Four years ago, at the behest of the Connecticut Department of Children and Families and with the support of the Annie E. Casey Foundation, the investigators developed a comprehensive community-based treatment program to address the problem of co-occurring parental substance abuse and child maltreatment. Importantly, and in collaboration with investigators at the Johns Hopkins University, this program, named Building Stronger Families (BSF), integrated an innovative evidence-based treatment for adult substance abuse (i.e., Reinforcement-Based Therapy [RBT]; Jones, Wong, Tuten, & Stitzer, 2005) with an evidence-based treatment of child abuse and neglect (i.e., Multisystemic Therapy for Child Abuse and Neglect [MST-CAN]; Swenson, Schaeffer, Henggeler, et al., 2009). The purpose of the present proposal is to request funding for a randomized trial of the BSF model, now 4 years in operation. A feasibility review and quasi-experimental evaluation of BSF have been completed. Regarding feasibility, the Department of Children and Families, which funds the clinical services, and the Annie E. Casey Foundation, which funds the quality assurance (e.g., treatment manuals, training) and ongoing involvement of the investigators, remain enthusiastic supporters of BSF. Moreover, BSF acceptability and feasibility are supported by 87 percent participant recruitment and 93 percent treatment completion rates. Regarding preliminary outcomes, a matched-comparison study (N = 52) indicated that BSF was significantly more effective than Comprehensive Community Treatment (CCT) at preventing reabuse, with BSF achieving an average reduction of 75 percent in substantiated reports of maltreatment at 24 months. Further, BSF participants were 50 percent less likely to have experienced an out-of- home placement at 18 months and 65 percent less likely at 24 months, with results approaching significance at 24 months. In light of these promising results, the proposed study aims to provide a rigorous and comprehensive evaluation of BSF by comparing this model to CCT on key clinical and system indices from baseline through 18 months. The intervention addresses the most prevalent, challenging, costly, and understudied area within the child welfare and parental substance abuse fields. If successful, this research could provide a substantial contribution, positively impacting the lives of millions of the most vulnerable families.